Golden Eagles
Beginning in 1963 under the guidance of John Craighead, research efforts began examining Golden Eagle Ecology in South-Central Montana. At that time, research was focused on nesting ecology, prey selection and effects of pesticides on the birds. While that alone was incredibly powerful information for the time, it also laid the foundation for what is now the longest running dataset on Golden Eagle nesting trends in all of North America.
A Decline In Number of Migrating Golden Eagles
In the mid 1990’s, Derek Craighead returned to resurvey the study site his father had been so integral in researching 30 years prior. Upon his return, Derek documented eagles in many of the historic territories located in the 1960’s and found a similar nest density as well as productivity rate of the birds in this Golden Eagle paradise. At that time, the population in the Rocky Mountain region was thought to be recovered and stable so was of little concern to biologists. But this period also marked the beginning of a decline in the number of migrating Golden Eagle’s counted annually at established locations along known migration routes. This was cause for biologists and land managers to start paying closer attention and concern started to build.
Changing Trends
While migration counts are invaluable for monitoring population trends, they are unable to provide the cause of changing trends. With that in mind, CBS biologists saw an opportunity to continue the research started almost 50 years ago on Golden Eagle nesting demographics in South-Central Montana and collect information that could potentially help mitigate declines of these birds in the Rocky Mountain west.
Beginning in 2010, personnel from Craighead Beringia South embarked on the third phase of the Golden Eagle nesting project. The entire study site was revisited in the spring, during the early nesting period, and locations of current territories and active nest sites were documented. During this initial visit, we were able to document the use of nest sites that dated all the way back to the original survey period meaning birds had been nesting in the same area for at least 50 years! After that initial visit, the crew went back 2 additional times to assess productivity. The number of young entering the population (i.e. productivity) is potentially the most critical factor affecting the population decline and is a missing piece of the puzzle that managers need to make informed decisions. With one year of data under our belt, the team is continuing the study in 2011 to substantiate the findings and add current numbers to the incredible historic dataset we have at our fingertips. For the latest on the study check out the 2011 Interim Report.
Craighead Beringia South's Avian Program Director Bryan Bedrosian oversees this project and works with Ross Crandell, CBS biologist.